1. Field
The present disclosure relates to acid-resistant yeast cells and a method of preparing lactate by using the acid-resistant yeast cells.
2. Description of the Related Art
Organic acids are widely used in various industries. For example, lactate is an organic acid that is widely used in various industries such as food, pharmaceuticals, chemicals, and electronics. Lactate is a low-volatile material that is colorless, odorless, and water-soluble. Lactate is non-toxic to humans, and thus, lactate is used as a flavoring agent, an acidifier, and a preservative. Lactate is also used as a source of polylactic acid (PLA) that is an environmentally friendly, biodegradable plastic known as an alternate polymeric material.
An organic acid may be dissociated into hydrogen ions and negative ions of the organic acid at an acidity higher than a pKa value of the organic acid, for example, under a neutral condition. However, organic acids such as lactic acid exist as free acids, which do not have electromagnetic force under an acidic condition that has a lower pKa than a pKa of the organic acid. The anionic form of the organic acid may not pass through a cell membrane but a free acid form of the organic acid may pass through the cell membrane. Thus, an organic acid outside the cell membrane may flow into a cell from an environment with high concentration of the organic acid, which may decrease intracellular pH. Also, the anionic form of the organic acid is disadvantageous in that a salt needs to be added thereto to separate the organic acid in a salt form. As a result, a cell lacking acid-resistance may lose activity and die under an acidic condition including one or more organic acids.
Thus, there remains a need for an acid-resistant microorganism that retains activity when exposed to acidic conditions.